Ratchet bolt assembly

Abstract

This invention provides a self-retracting and self-locking bolt assembly for fixed attachment to a workpiece to removably secure the workpiece to a second workpiece containing a mating internally threaded fastening device. A bolt has a shank with rolled threads on its outer end and an exterior shank shoulder, adjacent the head, which faces the threaded section. A collar circumscribes the shank and is slidably retained on the shank, by the rolled threads, between the shoulder and the rolled threads. The head is axially spring-biased away from the collar. The collar is in turn slidably and nonrotatably retained coaxially within the longitudinal passage through a cylindrical ferrule. The collar is also axially spring-biased, within the ferrule, towards the shank shoulder with a force greater than the head-biasing force. As the bolt is pressed axially through the collar and ferrule, the shoulder enters the ferrule passage, contacts the collar and presses it through the passage against the spring force upon the collar. During rotational tightening of the bolt, mating ratchet teeth upon the contacting surfaces of the shoulder and collar slip past one another. After tightening, the spring-enforced contact between the mating ratchet teeth precludes rotational bolt loosening from vibration and the like but permits subsequent loosening with the wrench. When the bolt is disengaged from its mating fastening device, and the wrench removed, the bolt and collar are spring-returned to their fully biased positions.

I claim: 
     
       1. A self-locking fastener device comprising a bolt having a head,   a shank extending from said head,   and threads on the outer end of said shank,     a first ratchet member adjacent said head, said first ratchet member being rotatable with said shank and having teeth facing toward said outer end of said shank,     a retaining member having means for attachment to a workpiece,   a second ratchet member, said second ratchet member having an opening receiving said shank inwardly of said threads,     means for retaining said second ratchet member on said shank with freedom for axial movement relative to said shank inwardly of said threads, while permitting relative rotation of said shank and said second ratchet member, said second ratchet member having teeth facing toward and engageable with said teeth of said first ratchet member,   said second ratchet member being retained by said retaining member with freedom for limited axial movement thereof between a first position relatively adjacent said head of said bolt and a second position relatively remote therefrom, while being prevented from substantial rotation relative to said retaining member,     a first spring biasing said second ratchet member toward said first position,   and a second spring engaging said bolt and exerting a force biasing said bolt toward a retracted position and said second ratchet member toward said second position, said first spring being stronger than said second spring whereby said second ratchet member is maintained in said first position upon axial advancement of said bolt until said first ratchet member engages said second ratchet member, and thereafter said second ratchet member is moved by said first ratchet member toward said second position.     
     
     
       2. A device as recited in claim 1 in which said first spring engages one side of said second ratchet member and said second spring engages the opposite side of said second ratchet member and the undersurface of said head. 
     
     
       3. A device as recited in claim 2 in which said teeth of said second ratchet member are on said opposite side thereof, and said second spring engages said opposite side of said second ratchet member radially outwardly of said teeth of said second ratchet member. 
     
     
       4. A device as recited in claim 1 in which said retaining member includes a first end adjacent said head, a second end remote from said head, and an abutment at said first end for limiting movement of said second ratchet member to said first position. 
     
     
       5. A device as recited in claim 4 in which said means for attachment to a workpiece includes a wall at said second end bendable to form a flange for engaging such a workpiece. 
     
     
       6. A self-locking fastening device comprising a bolt having a head,   a shank extending from said head,   and threads on the outer end of said shank, said threads having a greater maximum diameter than the diameter of said shank inwardly thereof,       a first ratchet member adjacent said head, said first ratchet member being rotationally and axially fixed relative to said shank and having teeth facing toward said outer end of said shank,     a ferrule receiving said shank, said ferrule including means for attachment to a workpiece,     a second ratchet member in said ferrule, said second ratchet member having an opening receiving said shank inwardly of said threads, said maximum diameter of said threads being greater than the diameter of said opening in said second ratchet member whereby said second ratchet member is retained on said shank and is slidable axially along said shank inwardly of said threads,     said second ratchet member having teeth facing toward said first ratchet member,   said second ratchet member and said ferrule having interengaging means for preventing rotation of said second ratchet member relative to said ferrule while permitting axial movement of said second ratchet member relative to said ferrule,   said ferrule having an abutment at one end thereof for retaining said second ratchet member in said ferrule while permitting said teeth of said second ratchet member to engage said teeth of said first ratchet member,     a first spring in said ferrule engaging one side of said second ratchet member and biasing said second ratchet member toward said abutment,   and a second spring circumscribing said shank, one end of said second spring engaging the undersurface of said head and the opposite end of said second spring engaging the opposite side of said second ratchet member,   said first spring being stronger than said second spring, whereby said second ratchet member is retained in engagement with abutment upon axial advancement of said bolt until said first ratchet member engages said second ratchet member, and thereafter said second ratchet member is moved by said first ratchet member toward the opposite end of said ferrule.     
     
     
       7. A device as recited in claim 6 wherein said first ratchet member includes a sleeve circumscribing said shank with one end thereof adjacent said head, said teeth of said first ratchet member being formed on the end of said sleeve remote from said head. 
     
     
       8. A device as recited in claim 7 in which said shank includes a straight knurl, the inner wall of said sleeve being embedded in said knurl so as to prevent relative rotation of said sleeve and said shank. 
     
     
       9. A device as recited in claim 6 wherein said interengaging means for preventing rotation of said annular member relative to said ferrule includes slot means in said ferrule, and projecting means on said annular member received in said slot means, said slot means extending axially within said ferrule for permitting axial movement of said annular member relative to said ferrule while precluding rotation of said annular member relative to said ferrule. 
     
     
       10. A device as recited in claim 9 wherein said slot means is defined by the tip portions of a hexagon, thereby defining a plurality of slots, and wherein said annular member has a hexagonal periphery having tip portions received in said plurality of slots. 
     
     
       11. A device as recited in claim 10 wherein said means for attachment includes a relatively thin-walled end portion of said ferrule adapted for being bent outwardly for forming a flange for holding said ferrule to said workpiece. 
     
     
       12. A device as recited in claim 6 wherein said abutment is defined by a relatively thin-walled end portion of said ferrule bent inwardly to form a flange.